cranium and mandible imaging protocol: a guide for...
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CRANIUM AND MANDIBLE IMAGING PROTOCOL: A GUIDE FOR PUBLICATION-QUALITY DIGITAL PHOTOGRAPHY OF THE SKULL PROTOCOLO PARA IMAGENES DE CRÁNEO Y MANDÍBULA: UNA GUÍA PARA PUBLICACIÓN DE FOTOGRAFÍA DIGITAL CON ALTA CALIDAD
KELSIE HART UNIVERSITY OF CALIFORNIA, BERKELEY SOCORRO BÁEZ-MOLGADO HUMAN EVOLUTION RESEARCH CENTER, UNIVERSITY OF CALIFORNIA, BERKELEY
FOROST Occasional Publications • No. 2 • August 2013
FOROST Occasional Publications
Materials
1. Choose a camera and accessories
DSLR camera with resolution of over three megapixels
55 mm lens with an aperture that can be tightened to at least f16
Live computer interface
Back-up system for image storage
Photo editing software (such as Adobe Photoshop™)
Camera copy stand
Tripod
2. Camera and copy stand setup
3. Cranium setup
Specimen safety
Be aware of specimen at all times
Always wear gloves
Never place specimen directly on a hard surface- use cushions or foam
Never leave specimen unattended
Place all objects at a safe distance
Secure cords with tape
Don’t use metal rulers for alignments
4. Alignment of cranium
Frankfurt Horizontal (right and left porion and left orbitale)
Approximate alignment of mastoid processes
Approximate alignment of sagittal plane
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.1 Anterior view of cranium
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.2 Basilar / Inferior view of cranium
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.3 Left lateral view of cranium
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.4 Right lateral view of cranium
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.5 Superior view of cranium
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
4.6 Posterior view of cranium (use tripod)
Camera and tripod setup
4.6 Posterior view of cranium (use tripod)
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Photography of the Mandible
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Anterior view of mandible
Left and right lateral views of mandible
Superior view of mandible (use camera copy stand)
5. Lighting setup
Most important and time-consuming step
Many different ways to achieve proper lighting
Need to experiment and take many test photographs- in conjunction with camera settings
Goal: indirect, oblique illumination from all directions- show topography while minimizing heavy shadows
Sample lighting method
6. Adjust the camera settings
Conditions: still photography, large depth of field, low-light, stabilized DSLR camera
First: 55 mm lens, manual mode, no flash, 10 second timer
The ‘exposure triangle’:
Aperture / f-stop
ISO
Shutter speed
6.1 Aperture / f-stop
Mechanically controls the size of the aperture (iris) and thus the depth of field
For cranial photography, we need a large depth of field
A high f-stop will shrink the iris and enlarge the depth of field
A high f-stop can cause distortion
55 mm lens at 1.2 m and f 16 is recommended and should not cause distortion
6.2 ISO
Controls the camera’s sensitivity to light
High ISO increases sensitivity to light but can cause image to be grainy
Use camera’s optimal ISO and adjust the exposure using the shutter speed
6.3 Shutter speed
Controls the duration of exposure
Because we use a stabilized camera and low-light conditions, a long exposure (slow shutter speed) can be used
Any vibration of the camera will cause distortion
Use copy stand / tripod and 10 second timer
7. Check the camera for a final look at the image
The cranium should be centered in the camera frame and properly aligned
The black velvet should lie smoothly and the scale should not touch the sides of the cranium.
The scale and cranium should be fully visible, in focus, and well-lit.
8. Take the photograph using a 10 second timer
9. Review the photograph (on the computer)
Make sure the cranium is well-lit everywhere and in focus
The cranial features should be visible in sharp detail when viewed at a zoom value of 100% (where each screen pixel equal one image pixel).
If necessary, make adjustments and retake the photo.
Label the image according to a desired naming protocol.
When saving the file, do not use the JPEG format or compress the TIFF.
10. Edit the photo (optional)
Brightness, contrast, and other non-distorting filters are acceptable
The scale can be straightened or replaced with a digital scale rendered in the same proportions.
The background, except for a small margin around the cranium itself, can be replaced with solid black
Unedited Photo (left lateral view)
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Left lateral view after editing in PhotoshopTM
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).
Acknowledgements
Erika Najarro University of Washington
Dr. Sabrina B. Sholts Stockholm University, Sweden
Dr. W. Henry Gilbert California State University, East Bay; Human Evolution Research Center, University of California, Berkeley
Dr. Carlos Serrano, IIA, and UNAM
Phoebe A. Hearst Museum of Anthropology , UC Berkeley
Human Evolution Research Center, UC Berkeley